MOTH 7 E POWER OF SERPENTS. 271 



wonderful elasticity of limb did not assist him in the hour of 

 need? 



The toad has no agility to depend upon ; but by day he 

 perfectly understands the art of concealment under stones or 

 mosses, or in the roots of trees ; and the acrimonious fluid 

 which he suddenly discharges when disturbed, or which, on irri- 

 tation, exudes from his skin, may also serve to keep off many 

 an enemy. 



The snakes seem, at first sight, more defenceless than all the 

 other reptiles, as they are altogether deprived of feet ; and yet we 

 see them glide along with great celerity, and apparently without 

 an effort. Thus it is evident that a most excellent locomotive 

 apparatus must lie concealed within their cylindrical and naked 

 body ; and a closer inspection teaches us that, by an admirable 

 mechanism, their ribs are made to perform the office of legs. 

 For while we only possess twelve pairs of these bones, joined 

 together in front by means of the breastbone and cartilaginous 

 processes, and serving merely to assist respiration, the ribs of 

 serpents are exceedingly numerous, varying, according to the 

 proportions of the species, from fifty-one pairs to three 

 hundred and twenty. There is no vestige of a breastbone, so 

 that each rib is capable of individual motion ; and this faci- 

 lity of action is still further increased by each pair of ribs being 

 moveably articulated, by means of two slight concave surfaces, 

 with the corresponding vertebras, forming a kind of double ball 

 and socket-joint. Numerous strong muscles attach these long 

 levers to the scuta or scales of the skin, while others run from 

 scale to scale and from rib to rib ; and thus we can easily com- 

 prehend how, with such a complicated system of pulleys and 

 points of attachment, the reptile bringing up the tail towards 

 the head by bending the body into one or more curves, and then 

 again resting upon the tail and extending the body- is able to 

 shoot rapidly along, not only upon smooth ground or over the 

 rough bark of trees, but even from branch to branch ; as the 

 smallest hold suffices for its stretching-out its body at a foot's 

 length into the air, and thus reaching another sallying-point for 

 further progress. Thus, also, the serpent does not feel the want 

 of legs, which would indeed have been a great source of inconveni- 

 ence while creeping through the dense bushes or tangled roots, or 

 the masses of dead leaves that form its favourite haunts ; and 



